SQL Server: Index
- Indexes make database access faster. Without index your queries will run but indexes can increase the performance dramatically.
- You can define multiple indexes for a table and select the index that is required for current operations.
- Only one clustered index is supported for a table
- To get advantage of indexes you have to mention the index related constraints in your where clause like where last_name =’xyz’
- If you have indexes on two or more columns, in where clause mention the first column name/constraint first [that was first in the index creation].
- A clustered index contains table data sorted in the index where a non-clustered index contains reference to the table data or clustered index. Non-clustered indexes are both physically and logically independent of table data.
Index Best Practices
- Select a column/(columns) for indexes that will provide good uniqueness and selectivity otherwise indexing may degrade the performance
- Create indexes that result in lower number of rows to be searched
- Create indexes that select a range of rows
- Try to create clustered index with as uniqueness as possible
- Keep indexes as narrow as possible (not many/unnecessary columns)
- Don’t index very small table
In SQL server, you can create indexes through your sql statements or using the development studio interface.
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Post Data:2011-01-21 05:26:33
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